method to determine the psychological impact of entertainment or individual presenters

ABSTRACT

A method for determining the psychological impact of entertainment material having at least first and later episodes, the method including the steps of: (a) presenting a first episode to a target group of subjects, (b) after a predetermined period of time, presenting the later episode to the target group of subjects; (c) determining brain activities of the target group of subjects whilst the later episode is being presented to the target group of subjects; and (d) evaluating the psychological impact of the entertainment material by reference to the levels of brain activities determined in step (c). The method of presenting material and determining brain activities also being used for determining the suitability of an actor from a group of actors or selecting a person from a group of persons for a public role.

At present, the likely commercial success of newly created entertainmentmaterial such as television programs, feature films or the response toan individual presenting a message or an individual seeking publicoffice is typically estimated by questionnaires with test audiences orfocus groups drawn from test audiences that have viewed the material orthe individual. Such methods are now recognized as deficient in tappingthe emotional responses of the test audiences. It is such emotionalresponses such as the level of engagement with the material orindividual, the sense of excitement, the likeability of variouscharacters that play a crucial role in the commercial success orotherwise of the entertainment material.

An object of the present invention is to provide a more accurate methodof measurement of the likely commercial success of entertainmentmaterial or response to an individual.

Generally speaking, the present invention provides a method that relieson the measurement of brain activity, rather than verbal responses todetermine the psychological and especially the emotional responses toentertainment material or individuals.

According to the present invention there is provided a method fordetermining the psychological impact of entertainment material having atleast first and later episodes, the method including the steps of:

(a) presenting a first episode to a target group of subjects;

(b) after a predetermined period of time, presenting the later episodeto the target group of subjects;

(c) determining brain activities of the target group of subjects whilstthe later episode is being presented to the target group of subjects;and

(d) evaluating the psychological impact of the entertainment material byreference to the levels of brain activities determined in step (c).

The invention also provides a method for determining the suitability ofan actor from a group of actors for a role in entertainment materialincluding the steps of:

(a) causing each of actors to separately perform by reading the samescript or acting the same role;

(b) presenting each of the actor's performances in step (a) to a testaudience;

(c) determining brain activities of the test audience separately foreach of the performances; and

(d) determining the suitability of the actors for the role by referenceto the brain activities determined in step (c).

The invention also provides a method of determining the selecting of aperson from a group of persons for a public role, the method includingthe steps of:

(a) causing each person to separately make a presentation which isassociated with the public role;

(b) presenting the each of the presentations of step (a) to a testaudience;

(c) determining brain activities of the test audience separately foreach of the persons; and

(d) selecting a person for the role by deference to the brain activitiesdetermined in step (c).

The invention also provides a system for determining the psychologicalimpact of entertainment material having at least first and laterepisodes, the system including:

(a) display means for displaying a later episode of the entertainmentmaterial to a target group of subjects who have earlier viewed the firstepisode of the entertainment material;

(b) determining means for determining brain activities of the targetgroup of subjects whilst the later episode is being presented to thetarget group of subjects; and

(c) evaluating means for evaluating the psychological impact of theentertainment material by reference to the levels of brain activitydetermined by said determining means.

The invention also provides a method of evaluating actors performing inentertainment material, the method including the steps of:

(a) presenting the entertainment material in which one or more actorsperform to an audience;

(b) determining brain activities of the audience during presentation ofthe entertainment material in step (a);

(c) averaging brain activity levels separately for each of the actorswhen they appear in the entertainment material; and

(d) evaluating the psychological impact of each of the actors byreference to the separate brain activities determined in step (c).

Brain activity is measured while subjects view an individual addressingan audience or some entertainment material. The entertainment materialcould comprise an episode from an established television program or anewly created pilot program. The material could also be presented in theform of an animatic, or a story board.

In one embodiment, the procedure to evaluate an established program or anewly developed pilot episodes of a program is described as follows:

-   1. Individuals drawn from the target group or likely audience for    the program view one or two episodes of the entertainment program.-   2. On the following day, brain activity is measured while subjects    view the next episode of the program.

In the situation where only animatics or story boards are available,brain activity is measured while subjects view the animatic or storyboard.

To determine the likely popularity of a completed program or earlymaterial, the most important measure is that of Engagement and is givenby the weighted average of brain activity in 4 frontal and prefrontalsites. This is given by the following expression:

engagement=(b ₁*brain activity at electrode F ₃ +b ₂*brain activity atelectrode P _(p1) +b ₃*brain activity at electrode F ₄ +b ₄*brainactivity at electrode F _(p2))

where b₁=0.1, b₂=0.4, b₃=0.1, b₄=0.4   Equation 1

If inverse mapping techniques are used, the relevant expression is:

engagement=(d ₁*right orbito frontal cortex (in vicinity of Brodman area11)+d ₂*right dorso-lateral prefrontal cortex (in vicinity of Brodmanarea 9)+d ₃*left orbito frontal cortex (in vicinity of Brodman area11)+d ₄*left dorso-lateral prefrontal cortex (in vicinity of Brodmanarea 9))

where: d₁=0.1, d₂=0.4, d₃=0.1, d₄=0.4   Equation 2

The engagement measure can also be used to estimate the likelypopularity of program ideas when they are presented to a test audiencein the form of animatics or story boards. Higher engagement whensubjects view the animatic or story board will be associated with ahigher likelihood that the finished program will be popular with thetest audience.

Audience response either to an individual or to various characters inthe entertainment material can also be estimated from brain activity.Greater audience acceptance of an individual or an actor is indicated byhigher engagement when that actor is featured.

The likeability or the extent to which the individual or actor is likedby the audience is indicated by the Attraction-Repulsion measure.

Attraction Repulsion (sometimes termed like-dislike) is given by thedifference between brain activity at left frontal/prefrontal and rightfrontal/prefrontal regions. Attraction is indicated by a larger brainactivity in the left hemisphere compared to the right while Repulsion isindicated a larger brain activity in the right hemisphere compared tothe left.

Attraction=(a ₁*brain activity recorded at electrode F ₃ +a ₂*brainactivity recorded a electrode F _(p1) −a ₃*brain activity recorded atelectrode F ₄ −a ₄*brain activity recorded at electrode F _(p2))

where a₁=a₂=a₃=a₄=1.0   Equation 3

A positive value for the attraction measure is associated with theparticipants finding the character or individual attractive and likedwhile a negative measure is associated with repulsion or dislike.

If inverse mapping techniques are used, the relevant expression is:

Attraction=(c ₁*brain activity at right orbito-brain activity at frontalcortex (in vicinity of Brodman area 11)+c ₂*brain activity at rightdorso-lateral prefrontal cortex (in vicinity of Brodman area 9)+c₃*brain activity at left orbito-frontal cortex (in vicinity of Brodmanarea 11)+c ₄*brain activity at left dorso-lateral prefrontal cortex(vicinity of Brodman area 9))

where c₁=1, c₂=1, c₃=1, c₄=1   Equation 4

The memorability or extent to which an actor's role is encoded inlong-term memory is dependent upon long term memory encoding for detailsand verbal memories associated with an actor's role. This is indicatedby SSVEP phase advance or amplitude change at left frontal region,preferably approximately equidistant from left hemisphere electrodes C₃,F₃ and F₇ at the time that the actor is featured. If inverse mappingtechniques are used, the relevant location in the left cerebral cortexis the vicinity of Brodmans areas 6, 44, 45, 46 and 47.

Long term memory encoding for emotional and non-verbal memoriesassociated with an actor's role. This is indicated by SSVEP phaseadvance or amplitude change at left frontal region, preferablyapproximately equidistant from left hemisphere electrodes C₄, F₄ and F₈at the time that the actor is featured. If inverse mapping techniquesare used, the relevant location in the right cerebral cortex is thevicinity of Brodmans areas 6, 44, 45, 46 and 47.

The emotional excitement associated with a speech given by an individualor a program or a scene in a program is given by the Emotional Intensitymeasure.

Emotional intensity, indicated by brain activity at rightparieto-temporal region, preferable approximately equidistant from righthemisphere electrodes O₂, P₄ and T₆. If inverse mapping techniques areused, the relevant location in the right cerebral cortex is the vicinityof the right parieto-temporal junction.

The brain activity measures of Engagement, Attraction-Repulsion andEmotional Intensity can also be used to select the most suitableperformer or actor for a given role. In this case, an audience wouldview each of the applicants for a part performing a given scene in aprogram. The actor eliciting the highest level of Engagement andLikeability (on the Attract-Repulsion score) would be the most suitableone for the role. In the case of an individual giving an election speechor a presentation, the measures of Engagement, Attraction-Repulsion andEmotional Intensity associated with different points made in the speechwould enable identification of the issues that elicit the strongestresponses in the audience. The issues that elicit the strongestresponses are thus those that have the greatest impact on the wideraudience.

This method of evaluating entertainment material can also be used withdifferent media such as entertainment delivered to a computer over theinternet or entertainment delivered to a mobile phone or other digitalmedia.

Measuring Brain Activity

A number of methods are available for measuring brain activity. The mainfeature they must possess is adequate temporal resolution or thecapacity to track the rapid changes in brain activity. Spontaneous brainelectrical activity or the electroencephalogram (EEG) or the brainelectrical activity evoked by a continuous visual flicker that is theSteady State Visually Evoked (SSVEP) are two examples of brainelectrical activity that can be used to measure changes in brainactivity with sufficient temporal resolution. The equivalent spontaneousmagnetic brain activity or the magnetoencephalogram (MEG) and the brainmagnetic activity evoked by a continuous visual flicker Steady StateVisually Evoked Response (SSVER).

Electroencephalogram and Magnetoencephalogram (EEG and MEG)

The EEG and MEG are the record of spontaneous brain electrical andmagnetic activity recorded at or near the scalp surface. Brain activitycan be assessed from the following EEG or MEG components.

1. Gamma or High Frequency EEG or MEG Activity

This is generally defined as EEG or MEG activity comprising frequenciesbetween 35 Hz and 80 Hz. Increased levels of Gamma activity areassociated with increased levels of brain activity, especially concernedwith perception. (Fitzgibbon S P, Pope K J, Mackenzie L, Clark C R,Willoughby J O. Cognitive tasks augment gamma EEG power. ClinNeurophysiol. 2004: 115:1802-1809).

If scalp EEG gamma activity is used as the indicator of brain activity,the relevant scalp recording sites are listed above. If EEG gammaactivity at the specific brain regions listed above is used as theindicator brain activity then inverse mapping techniques such as LORETAmust be used (Pascual-Marqui R, Michel C, Lehmann D (1994): Lowresolution electromagnetic tomography: a new method for localizingelectrical activity in the brain. Int J Psychophysiol 18:49-65).

If MEG gamma activity at the specific brain regions listed above is usedas the indicator of brain activity, then the multi-detector MEGrecording system must be used in conjunction with an MEG inverse mappingtechnique (see Uutela K, Ha{umlaut over ( )}ma{umlaut over (b)}{umlautover ( )}la{umlaut over ( )}inen M, Somersalo E (1999): Visualization ofmagnetoencephalographic data using minimum current estimates. Neuroimage10:173-180 and Fuchs M, Wagner M, Kohler T, Wischmann H A (1999): Linearand nonlinear current density reconstructions, J Clin Neurophysiol16:267-295).

2. Frequency of EEG or MEG Alpha Activity

Brain activity may also be indexed by changes in the frequency of theongoing EEG or MEG in the alpha frequency range (8.0 Hz-13.0 Hz).Increased frequency is an indication of increased activity. Thefrequency needs to me estimated with high temporal resolution. Twotechniques that can be used to measure ‘instantaneous frequency’ arecomplex demodulation (Walter D, The Method of Complex Demodulation.Electroencephalog. Clin. Neurophysiol, 1968 Suppl 27:53-7) and the useof the Hilbert Transform (Leon Cohen, “Time frequency analysis”,Prentice-Hall, 1995). Increased brain activity is indicated by anincrease in the instantaneous frequency of the EEG in the alphafrequency range.

If the frequency of scalp EEG alpha activity is used as the indicator ofbrain activity, the relevant scalp recording sites are listed above. Ifthe frequency of EEG alpha activity at the specific brain regions listedabove is used as the indicator brain activity then inverse mappingtechniques such as LORETA must be used (Pascual-Marqui R, Michel C,Lehmann D (1994): Low resolution electromagnetic tomography: a newmethod for localizing electrical activity in the brain. Int JPsychophysiol 18:49-65).

If the frequency of MEG alpha activity at the specific brain regionslisted above is used as the indicator of brain activity, then themulti-detector MEG recording system must be used in conjunction with anMEG inverse mapping technique (see Uutela K, Ha{umlaut over ()}ma{umlaut over ( )}la{umlaut over ( )}inen M, Somersalo E (1999):Visualization of magnetoencephalographic data using minimum currentestimates. Neuroimage 10:173-180, and Fuchs M, Wagner M, Kohler T,Wischmann H A (1999): Linear and nonlinear current densityreconstructions, J Clin Neurophysiol 16:267-295).

-   3. SSVEP or SSVER Phase as an Indicator of Brain Activity

Brain activity may also be indicated by the phase of the Steady StateVisually Evoked Potential (SSVEP) or the Steady State Visually EvokedResponse (SSVER).

U.S. Pat. Nos. 4,955,938; 5,331,969; and 6,792,304 (the contents ofwhich are hereby incorporated herein by reference) disclose techniquefor obtaining a steady state visually evoked potential (SSVEP) from asubject. This technique can also be used to obtain a steady statevisually evoked response (SSVER). These patents disclose the use ofFourier analysis in order to rapidly obtain the SSVEP and SSVER phaseand changes thereto. The preferred way in which SSVEP and SSVERamplitudes and phases are calculated are summarised below.

SSVEP and SSVER Amplitude and Phase

The digitized brain electrical activity (electroencephalogram or EEG)brain magnetic activity (MEG) together with timing of the stimulus zerocrossings enables one to calculate the SSVEP or SSVER elicited by theflicker at a particular stimulus frequency from the recorded EEG or MEGor from EEG or MEG data that has been pre-processed using IndependentComponents Analysis (ICA) to remove artefacts and increase the signal tonoise ratio. [Bell A. J. and Sejnowski T. J. 1995, An informationmaximisation approach to blind separation and blind deconvolution,Neural Computation, 7, 6, 1129-1159; T-P. Jung, S. Makeig, MWesterfield, J. Townsend, E. Courchesne and T. J. Sejnowskik,Independent component analysis of single-trial event-related potentialHuman Brain Mapping, 14(3):168-85,2001].

Calculation of SSVEP or SSVER amplitude and phase for each stimuluscycle for a given stimulus frequency. Calculation accomplished usedFourier techniques using Equations 5 and 6 below.

$\begin{matrix}{{a_{n} = {\frac{1}{S\; \Delta \; \tau}{\sum\limits_{i = 0}^{S - 1}{{f\left( {{nT} + {i\; \Delta \; \tau}} \right)}{\cos \left( {\frac{2\; \pi}{T}\left( {{nT} + {i\; \Delta \; \tau}} \right)} \right)}}}}}{b_{n} = {\frac{1}{S\; \Delta \; \tau}{\sum\limits_{i = 0}^{S - 1}{{f\left( {{nT} + {i\; \Delta \; \tau}} \right)}{\sin \left( {\frac{2\; \pi}{T}\left( {{nT} + {i\; \Delta \; \tau}} \right)} \right)}}}}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

Calculation of SSVEP Fourier components where a_(n) and b_(n) are thecosine and sine Fourier coefficients respectively. n represents the nthstimulus cycle, S is the number of samples per stimulus cycle (16), Δτis the time interval between samples, T is the period of one cycle andf(nT+iΔτ) is the EEG or MEG signal (raw or pre-processed using ICA).

$\begin{matrix}{{{{SSVEP}_{amplitude} = \sqrt{\left( {A_{n}^{2} + B_{n}^{2}} \right)}}\mspace{14mu} {or}\mspace{14mu} {{SSVER}_{amplitude} = \sqrt{\left( {A_{n}^{2} + B_{n}^{2}} \right)}}{{SSVEP}_{phase} = {a\; {\tan \left( \frac{B_{n}}{A_{n}} \right)}}}\mspace{14mu} {or}{{SSVER}_{phase} = {a\; {\tan \left( \frac{B_{n}}{A_{n}} \right)}}}}\;} & {{Equation}\mspace{14mu} 6}\end{matrix}$

Where A_(n) and B_(n) are overlapping smoothed Fourier coefficientscalculated by using Equation 7 below.

$\begin{matrix}{{A_{n} = {\sum\limits_{i = 1}^{i = N}{a_{n + i}/N}}}{B_{n} = {\sum\limits_{i = 1}^{i = N}{b_{n + i}/N}}}} & {{Equation}\mspace{14mu} 7}\end{matrix}$

Amplitude and phase components can be calculated using either singlecycle Fourier coefficients (a_(n) and b_(n)) or coefficients that havebeen calculated by smoothing across multiple cycles (A_(n) and B_(n)).

Equations 6 and 7 describe the procedure for calculating the smoothedSSVEP or SSVER coefficients for a single subject. For pooled data, theSSVEP or SSVER coefficients (A_(n) and B_(n)) for a given electrode areaveraged (or pooled) across all of the subjects or a selected group ofsubjects.

As the number of cycles used in the smoothing increases, the signal tonoise ratio increases while the temporal resolution decreases. Thenumber of cycles used in the smoothing is typically in excess of 5 andless than 130.

Equations 6 and 7 apply to scalp SSVEP data as well as brain electricalactivity inferred at the cortical surface adjacent to the skull anddeeper regions. Activity in deeper regions of the brain such as theorbito-frontal cortex or ventro-medial cortex can be determined using anumber of available inverse mapping techniques such as EMSE (SourceSignal Imaging, Inc, 2323 Broadway, Suite 102, San Diego, Calif. 92102,USA) and LORETA (Pascual-Marqui R, Michel C, Lehmann D (1994): Lowresolution electromagnetic tomography: a new method for localizingelectrical activity in the brain. Int J Psychophysiol 18:49-65). If theSSVER amplitude or phase changes at the specific brain regions listedabove are used as the indicator of brain activity, then themulti-detector MEG recording system must be used in conjunction with anMEG inverse mapping technique (see Uutela K, Ha{umlaut over ()}ma{umlaut over ( )}la{umlaut over ( )}inen M, Somersalo E (1999):Visualization of magnetoencephalographic data using minimum currentestimates, Neuroimage 10:173-180, and Fuchs M, Wagner M, Kohler T,Wischmann H A (1999): Linear and nonlinear current densityreconstructions, J Clin Neurophysiol 16:267-295).

The invention will now be further described with reference to theaccompanying drawings, in which:

FIG. 1 is a schematic view of a system of the invention;

FIG. 2 is a schematic view showing in more detail the manner in whichvisual flicker stimuli are presented to a subject;

FIG. 3 is a graph showing the opacity of the screen as a function ofradius;

FIG. 4 graphically shows the measures for viewing engagement for maleand female subjects for different types of entertainment material;

FIG. 5 graphically shows different measures of impact for threedifferent actors; and

FIG. 6 shows correlation between the techniques of the invention andknown assessment techniques.

FIG. 1 schematically illustrates a system 50 for determining theresponse of a subject or a group of subjects to audio-visual materialpresented on a video screen 3 and loudspeaker 2. The system includes acomputer 1 which controls various parts of the hardware and alsoperforms computation on signals derived from the brain activity of thesubject 7, as will be described below. The computer 1 also holds theimages and sounds which can be presented to one or more subjects 7 onthe screen 3 and/or through the loudspeaker 2.

The subject or subjects 7 to be tested are fitted with a headset 5 whichincludes a plurality of electrodes for obtaining brain electricalactivity from various sights on the scalp of the subject 7. In the eventthat the SSVER is used, the recording electrodes in the headset 5 arenot used and a commercial MEG recording system such as the CTF MEGSystem manufactured by VSM MedTech Ltd. of 9 Burbidge Street, Coquitlam,BC, Canada, can be used instead. The headset includes a visor 4 whichincludes half silvered mirrors 8 and white light Light Emitting Diode(LED) arrays 9, as shown in FIG. 2. The half silvered mirrors arearranged to direct light from the LED arrays 9 towards the eyes of thesubject 7. The LED arrays 9 are controlled so that the light intensitythere from varies sinusoidally under the control of control circuitry 6.The control circuitry 6 includes a waveform generator for generating thesinusoidal signal. In the event that the SSVER is used, the light fromthe LED array is conveyed to the visor via a fibre optic system. Thecircuitry 6 also includes amplifiers, filters, analogue to digitalconverters and a USB interface or a TCP interface or other digitalinterface for coupling the various electrode signals into the computer1.

A translucent screen 10 is located in front of each LED array 9. Printedon the screen is an opaque pattern. The opacity is a maximum in acircular area in the centre of the centre of the screen. Beyond thecircular area, the opacity falls off smoothly with radial distance fromthe circular area circumference, preferably, the opacity should fall offas a Gaussian function described by Equation 8. The screen reduces theflicker in the central visual field thus giving subjects a clear view ofthe visually presented material. The size of the central opaque circleshould be such as to occlude the visual flicker in the central visualfield between 1-4 degrees vertically and horizontally.

If r<R then P=1

If then P is given by Equation 8 below.

P=e ^(−(r−R)) ² ^(/G) ²   Equation 8

where P is the opacity of the pattern on the translucent screen. Anopacity of P=1.0 corresponds to no light being transmitted through thescreen while an opacity of P=0 corresponds to complete transparency.

R is the radius of the central opaque disk while r is the radialdistance from the centre of the opaque disk. G is a parameter thatdetermines the rate of fall-off of opacity with radial distance.Typically G has values between R/4 and 2R. FIG. 3 illustrates thefall-off of opacity with radial distance from the centre of the disk. InFIG. 3, R=1 and G=2R.

The computer 1 includes software which calculates SSVEP or SSVERamplitude and phase from each of the electrodes in the headset 5 or MEGsensors.

Details of the hardware and software required for generating SSVEP andSSVER are well known and need not be described in detail. In thisrespect reference is made to the aforementioned United States patentspecifications which disclose details of the hardware and techniques forcomputation of SSVEP. Briefly, the subject 7 views the video screen 3through the visor 4 which delivers a continuous background flicker tothe peripheral vision. The frequency of the background flicker istypically 13 Hz but may be selected to be between 3 Hz and 50 Hz. Morethan one flicker frequency can be presented simultaneously. The numberof frequencies can vary between 1 and 5. Brain electrical activity willbe recorded using specialized electronic hardware that filters andamplifies the signal, digitizes it in the circuitry 6 where it is thentransferred to the computer 1 for storage and analysis.

When using the SSVEP, brain electrical activity is recorded usingmultiple electrodes in headset 5 or another commercially availablemulti-electrode system such as Electro-cap (ECI Inc., Eaton, Ohio USA).When using the SSVER, commercial MEG recording system such as the CTFMEG System manufactured by VSM MedTech Ltd may be used. The number ofelectrodes or magnetic recording sites is normally not less than 8 andnormally not more than 128, typically 16 to 32.

Brain electrical activity at each of the electrodes is conducted to asignal conditioning system and control circuitry 6. The circuitry 6includes multistage fixed gain amplification, band pass filtering andsample-and-hold circuitry for each channel. Amplified/filtered brainactivity is digitized to 16-24 bit accuracy at a rate not less than 300Hz and transferred to the computer 1 for storage on hard disk. Thetiming of each brain electrical sample together with the time ofpresentation of different components of the audio-visual material arealso registered and stored to an accuracy of 10 microseconds. Theequivalent MEG recording system that is commercially available performsthe same functions.

SSVEP and SSVER amplitude and phase can be calculated in accordance withthe above.

While one or more subjects are viewing the images to be evaluated, thevisual flicker is switched on in the visor 4 and brain electricalactivity is recorded continuously on the computer 1.

At the end of the recording stage, the SSVEP or SSVER amplitude andphase are separately calculated for each individual. Once all recordingsare completed, group averaged data is calculated by averaging thesmoothed SSVEP opr SSVER amplitude and phase data from subjects to beincluded in the group (eg male, female, young, old).

EXAMPLE 1

The following procedure is used to evaluate the likely success of newentertainment material or the release of established entertainmentmaterial to a new target audience.

In this example, 50 to 200 participants drawn from the likely targetaudience for the test entertainment material are recruited into thestudy. All participants view at least one episode or part of theentertainment material at either one or more locations or in the home.In this Example, viewer engagement is important and accordingly theelectrodes in the headsets 5 are selected so as to enable engagement tobe calculated using the techniques described earlier. Brain activity isalso preferably determined using SSVEP. The engagement measures of thetarget audiences were separated into males and females and the resultswere plotted graphically in FIG. 4. FIG. 4 shows the engagement measuresfor the male and female audiences for five different types of programs,drama, travel, food, romance and documentary. Later, ideally no lessthan 24 hours later, brain activity is recorded while the participantsview a subsequent episode or part of the entertainment material asdescribed in more detail below.

To record brain activity, a selected number of subjects, say 50, areseated in a test room and the headsets 5 are placed on their heads. Thevisors 4 are then placed in position and adjusted so that the fovealblock by the screens 10 prevents the appearance of the flicker over thescreens 3 where the images are presented. The number of subjects in arecording session is variable and typically can vary from 1 to over 100.When pooling subjects to create the average response, the number ofsubjects whose data is to be included in the average should preferablybe no less than 16.

To minimize irritation or discomfort to the participants due to theflicker, the flicker stimulus is of variable intensity and only switchedto the highest intensity when material of interest to the client such asparticular segments of the program or specific actors appear on thescreen. During the periods that material of interest is not present onthe screen, the stimulus intensity is typically zero and never more than10% of the typical value used when material of interest is on thescreen. Preferably, the stimulus is not switched on abruptly but isslowly increased before the segment of interest is displayed anddecreased slowly after the end of the material of interest. Typically,the stimulus is increased linearly over a 30-60 second epoch prior tothe appearance of the material of interest so that it reaches itsmaximum value 60 seconds prior to the appearance of the material ofinterest. At the end of every segment of interest, a 30 second sequenceof still images of scenery and a musical accompaniment is presented.Typically, 60 images are presented over the period of 30 seconds witheach image present for about 0.5 seconds. Brain activity levels duringthe adjacent scene images are used as a reference level for brainactivity during the preceding segment of interest. This enables removalof any long-term changes in brain activity that may occur over the timecourse of the recording period.

Immediately the sequence of reference images at the end of the segmentof interest ends, the stimulus intensity is linearly reduced to theminimum value over a 30 second period. The slow linear increase anddecrease of stimulus intensity occurs for every segment of interest.

The likely audience engagement is given by the brain engagement measuretime averaged over at least 5 minutes of a typical segment of the newentertainment material ‘ engagement being calculated separately formales and females using the SSVEP techniques described above. As can beseen, for males, the programs with the highest engagement, and hence thegreatest likelihood of success are the drama and documentary programswhile for the females audience: the romance and food programs are mostlikely to be successful.

EXAMPLE 2

The invention can also be used to determine the psychological impact ofvarious actors which are featured in entertainment material. Thisexample is similar to Example 1 except that it is not necessary that thetarget audience has viewed an earlier episode of the entertainmentmaterial. Also the electrodes are selected so as to enable assessment ofengagement, like-dislike, memory for detail and verbal features, memoryfor non-verbal features and emotion, emotional intensity. Again, brainactivities are preferably measured using SSVEP techniques. In thisexample, a segment of entertainment material has three different actors,Actor 1, Actor 2 and Actor 3 featuring therein. Pooled responses areplotted graphically in FIG. 5 for the various hypothetical measures. Itis apparent from FIG. 5 that Actor 1 scores high on engagement,likeability and emotional intensity. This indicates that the audience isable to identify with the Actor 1 (indicated by high engagement), likesthe actor (high likeability) and finds the actor exciting (highemotional intensity). By contrast, Actor 2 is disliked and also arousesstrong emotion. This actor could be a good choice to play the part of avillain. Finally, Actor 3 is modestly engaging and the details of hisrole are well remembered (high memory for detail). Actor 3 could be wellsuited to educational roles where content is more important.

EXAMPLE 3

The invention can also be used to select an actor for a specific role.In this application, each of the possible actors is required to read thesame script or act the same role. Brain activity is then recorded fromthe test audience while viewing each of the applicants for the givenrole. Depending on the nature of the role (e.g. hero, villain etc.) theactor most effectively eliciting the desired psychological responsewould be selected for the part. Most relevant measures for the centralcharacters would be engagement, like-dislike, emotional intensity. Ifthe role also has an educational or information transfer component,long-term memory encoding would also be important.

It will be appreciated by those skilled in the art that the method ofthe invention compares very favourably with known techniques forevaluating the likely commercial success of entertainment material,suitability of actors or suitability of persons for public office. Inthe case of entertainment material, known analytical techniques can beused to determine a behavioural measure such as a Q-Score. The Q-Scoreindicates the desire the average viewer feels about watching aparticular program. Typically, the Q-Score is only available forprograms where a number of complete episodes have been viewed by thetarget audience. In the case of new entertainment material, this wouldbe quite time consuming and expensive to produce. By contrast, theassessment techniques based on engagement measures give an indication ofthe popularity based on the pilot program which of course is relativelyinexpensive to produce. FIG. 6 illustrates the average level ofengagement multiplied by 100 estimated from an audience of 150 subjectsover a five minute period when watching three television programs,sport, drama and travel. The level of engagement measured from brainactivity in accordance with the invention is shown in solid black bars.Corresponding data obtained from known Q-Score techniques are plotted instriped bars. It will be seen that there is a strong correlation betweenthe techniques of the invention and the Q-Score results, notwithstandingthat the techniques of the invention have been based on a pilotprograms.

Many modifications will be apparent to those skilled in the art withoutdeparting from the spirit and scope of the invention.

1. A method for determining the psychological impact of entertainmentmaterial having at least first and later episodes, the method includingthe steps of: (a) presenting a first episode to a target group ofsubjects; (b) after a predetermined period of time, presenting the laterepisode to the target group of subjects; (c) determining brainactivities of the target group of subjects whilst the later episode isbeing presented to the target group of subjects; and (d) evaluating thepsychological impact of the entertainment material by reference to thelevels of brain activities determined in step (c).
 2. A method asclaimed in claim 1 wherein step (e) includes the step of averaging thebrain activities determined in step (c).
 3. A method as claimed in claim1 wherein step (a) includes presenting first and second episodes to thetarget group of subjects.
 4. A method as claimed in claim 1 wherein theepisodes of the entertainment material are in the form of animatics orstory boards.
 5. A method as claimed in claim 1 wherein: step (c)includes presenting the later episode or episodes as segments in anaudiovisual presentation; after each segment, presenting referencematerial to the target group of subjects; determining reference levelsof brain activities whilst the reference material is presented to thetarget group of subjects; and removing the effect of long-term changesin brain activities by subtracting the reference levels of brainactivities from the levels of brain activity determined in step (c). 6.A method as claimed in claim 5 wherein the reference material includes asequence of still images.
 7. A method as claimed in claim 1 wherein step(b) is carried out by displaying the later episode on a video screen. 8.A method as claimed in claim 1 wherein step (c) is carried out bydetermining gamma or high frequency EEG or MEG activity.
 9. A method asclaimed in claim 1 wherein step (c) is carried out by detecting EEG orMEG activity in the frequency range 8 to 13 Hz.
 10. A method as claimedin claim 1 wherein step (c) is carried out by assessment of the phase ofsteady state visually evoked potentials (SSVEP) in EEG signals obtainedfrom the target group of subjects or by assessment of steady statevisually evoked responses (SSVER) in MEG signals obtained from thetarget group of subjects.
 11. A method as claimed in claim 1 whereinstep (c) includes the steps of placing electrodes at scalp sites toobtain output EEG signals which enable assessment of: engagement withthe entertainment material; attraction-repulsion of the entertainmentmaterial; long term memory encoding associated with the entertainmentmaterial; and/or emotional intensity associated with the entertainmentmaterial.
 12. A method as claimed in claim 11 including the step ofapplying a sinusoidally varying visual flicker stimulus to each subjectduring step (c) to thereby enable calculation of Fourier coefficientsfrom said output signals to thereby enable calculation of said SSVEPamplitudes and/or phase differences.
 13. A method as claimed in claim 12wherein said SSVEP amplitude and phase are calculated by the equations:${SSVEP}_{amplitude} = \sqrt{\left( {A_{n}^{2} + B_{n}^{2}} \right)}$${{SSVEP}_{phase} = {a\; {\tan \left( \frac{B_{n}}{A_{n}} \right)}}}\;$where: a_(n) and b_(n) are cosine and sine Fourier coefficientscalculated by the equations:$a_{n} = {\frac{1}{S\; \Delta \; \tau}{\sum\limits_{i = 0}^{S - 1}{{f\left( {{nT} + {i\; \Delta \; \tau}} \right)}{\cos \left( {\frac{2\; \pi}{T}\left( {{nT} + {i\; \Delta \; \tau}} \right)} \right)}}}}$$b_{n} = {\frac{1}{S\; \Delta \; \tau}{\sum\limits_{i = 0}^{S - 1}{{f\left( {{nT} + {i\; \Delta \; \tau}} \right)}{\sin \left( {\frac{2\; \pi}{T}\left( {{nT} + {i\; \Delta \; \tau}} \right)} \right)}}}}$where: a_(n) and b_(n) are the cosine and sine Fourier coefficientsrespectively where; n represents the nth flicker stimulus cycle; S isthe number of samples per flicker stimulus cycle; Δτ is the timeinterval between samples; T is the period of one cycle; f(nT+iΔτ) is theEEG signal (raw or pre-processed using ICA) obtained from saidpredetermined scalp sites; and wherein A_(n) and B_(n) are overlappingsmoothed Fourier coefficients calculated by using the equation:$A_{n} = {\sum\limits_{i = 1}^{i = N}{a_{n + i}/N}}$$B_{n} = {\sum\limits_{i = 1}^{i = N}{b_{n + i}/N}}$
 14. A method asclaimed in claim 13 including the steps of: obtaining EEG signals from aplurality of scalp sites of each subject; and utilising inverse mappingtechniques such as BESA, EMSA or LORETA to produce modified EEG signalswhich represent activity in deeper regions of the brain of each subjectsuch as the orbito-frontal cortex or the ventro-medial cortex.
 15. Amethod as claimed in claim 13 including the step of averaging theFourier coefficients A_(n) and B_(n) for a selected group of the targetsubjects and then calculating the SSVEP amplitudes and SSVEP phasedifferences for said group of subjects.
 16. A method as claimed in claim12 wherein the flicker signal is applied only to the peripheral visionof each subject.
 17. A method as claimed in claim 16 including the stepsof directing the flicker signal towards the eyes of each subject viafirst and second screens and wherein each screen includes an opaquearea, and wherein the method further includes the step of positioningthe screens to the relative position of each subject such that saidopaque areas prevent said flicker signal impinging on the fovea of eacheye of each subject.
 18. A method as claimed in claim 17 wherein theopacity of each screen decreases as a function of distance from itsopaque area so that the intensity of the flicker signal impinging oneach retina of each subject decreases in value from the central visionto the peripheral vision.
 19. A method as claimed in claim 18 includingthe step of applying a masking pattern to each screen to define theopacity thereof, the method including the step of applying the patternin accordance with a masking pattern function which provides zero or lowgradients for changes in opacity adjacent to its opaque area andperipheral areas thereof which define parts of the flicker signalimpinging on the peripheral vision of each subject.
 20. A method asclaimed in claim 19 wherein the opaque area of each screen is circularand wherein the masking pattern function is selected to be a Gaussianfunction, so that the opacity P of the screen is defined by theequation:P=e ^(−(r−R) ² ^(/G) ² where: r is the radial distance from the centreof the opaque area; and G is a parameter that determines the rate offall-off of opacity with radial distance, and wherein when r<R, P=1. 21.A method as claimed in claim 20 wherein G has a value in the range R/4and 2R.
 22. A method as claimed in claim 13 including the step ofapplying an electrode to the scalp of each subject at a site which isapproximately equidistant from sites O₂, P₄ and T₆, calculating SSVEPamplitudes and phase differences from EEG signals from said electrodewhereby the output signals indicate each subject's emotional intensityassociated with the entertainment material or selected actors.
 23. Amethod as claimed in claim 14 wherein the step of utilising inversemapping determines brain activity in the right cerebral cortex in thevicinity of the right parieto-temporal junction whereby the outputsignals indicate each subject's emotional intensity associated with theentertainment material or selected actors.
 24. A method as claimed inclaim 13 including the steps of applying an electrode to the scalp ofeach subject at the F₃, F₄, F_(p1) and F_(p2) sites, calculating SSVEPamplitudes and phase differences from EEG signals from said electrodes,calculating values for attraction-repulsion using the equation:attraction=(a ₁*SSVEP phase advance at electrode F ₃ +a ₂*SSVEP phaseadvance at electrode F _(p1) −a ₃*SSVEP phase advance at electrode F ₄−a ₄*SSVEP phase advance at electrode F _(p2))where a₁=a₂=a₃=a₄=1.0 whereby said values indicate each subject'slike-dislike towards the entertainment material or selected actors. 25.A method as claimed in claim 14 wherein the step of utilising inversemapping determines brain activity in: the right orbito-frontal cortex inthe vicinity of Brodman area 11; the right dorso-lateral prefrontalcortex in the vicinity of Brodman area 9; the left orbito frontal cortexin the vicinity of Brodman area 11; and the left dorso-lateralprefrontal cortex in the vicinity of Brodman area 9; and calculating avalue for attraction-repulsion using the equation:attraction=(c ₁*right orbito-frontal cortex (in vicinity of Brodman area11)+c ₂*right dorso-lateral prefrontal cortex (in vicinity of Brodmanarea 9)+c ₃*left orbito frontal cortex (in vicinity of Brodman area11)+c ₄*left dorso-lateral prefrontal cortex (vicinity of Brodman area9))where c₁=1, c₂=1, c₃=1, c₄=1, whereby said values indicate eachsubject's like-dislike towards the entertainment material or selectedactors.
 26. A method as claimed in claim 13 including the steps ofapplying electrodes to the scalp of each subject at F₃, F₄, P_(p1) andF_(p2) sites, calculating SSVEP amplitudes and phase differences fromsaid electrodes, calculating values for engagement in features of theadvertisement by a weighted mean SSVEP phase advance at said sites usingthe equation:engagement=(b ₁*SSVEP phase advance at electrode F ₃ +b ₂*SSVEP phaseadvance at electrode P _(p1) +b ₃*SSVEP phase advance at electrode F ₄+b ₄*SSVEP phase advance at Electrode F _(p2))where b₁=0.1, b₂=0.4, b₃=0.1, b₄=0.4, whereby said values indicate eachsubject's engagement in the entertainment material or selected actors.27. A method as claimed in claim 14 wherein the step of utilisinginverse mapping determines brain activity in: the right orbito frontalcortex in the vicinity of Brodman area 11; the right dorso-lateralprefrontal cortex in the vicinity of Brodman area 9; the left frontalcortex in the vicinity of Brodman area 11; and the left dorso-lateralprefrontal cortex in the vicinity of Brodman area 9, calculating SSVEPamplitudes and phase differences from said modified EEG signals fromsaid electrodes; and calculating a value for engagement using theequation:engagement=(d ₁*right orbito frontal cortex (in vicinity of Brodman area11)+d ₂*right dorso-lateral prefrontal cortex (in vicinity of Brodmanarea 9)+d₃*left orbito frontal cortex (in vicinity of Brodman area 11)+d₄*left dorso-lateral prefrontal cortex (in vicinity of Brodman area 9))where d₁=0.1, d₂=0.4, d₃=0.1, d₄=0.4, whereby said values indicate eachsubject's engagement in the entertainment material or selected actors.28. A method for determining the suitability of an actor from a group ofactors for a role in entertainment material including the steps of: (a)causing each of actors to separately perform by reading the same scriptor acting the same role; (b) presenting each of the actor's performancesin step (a) to a test audience; (c) determining brain activities of thetest audience separately for each of the performances; and (d)determining the suitability of the actors for the role by reference tothe brain activities determined in step (c).
 29. A method of determiningthe selecting of a person from a group of persons for a public role, themethod including the steps of: (a) causing each person to separatelymake a presentation which is associated with the public role; (b)presenting the each of the presentations of step (a) to a test audience;(c) determining brain activities of the test audience separately foreach of the persons; and (d) selecting a person for the role bydeference to the brain activities determined in step (c).
 30. A methodas claimed in claim 29 wherein step (c) includes the steps of placingelectrodes at scalp sites of the test audience to obtain EEG signalswhich enable assessment of: engagement; attraction-repulsion(like-dislike); and/or emotional intensity.
 31. A method of evaluatingactors performing in entertainment material, the method including thesteps of: (a) presenting the entertainment material in which one or moreactors perform to an audience; (b) determining brain activities of theaudience during presentation of the entertainment material in step (a);(c) averaging brain activity levels separately for each of the actorswhen they appear in the entertainment material; and (d) evaluating thepsychological impact of each of the actors by reference to the separatebrain activities determined in step (c).
 32. A method as claimed inclaim 31 wherein step (b) includes the steps of placing electrodes atscalp sites to obtain EEG signals which enable assessment of:engagement; attraction-repulsion (like-dislike); memory for detail andverbal features; memory for non-verbal features and emotion; and/oremotional intensity.
 33. A system for determining the psychologicalimpact of entertainment material having at least first and laterepisodes, the system including: (a) display means for displaying a laterepisode of the entertainment material to a target group of subjects whohave earlier viewed the first episode of the entertainment material; (b)determining means for determining brain activities of the target groupof subjects whilst the later episode is being presented to the targetgroup of subjects; and (c) evaluating means for evaluating thepsychological impact of the entertainment material by reference to thelevels of brain activity determined by said determining means.